Effect of Nucleation Density Model on CHF of Curved Surface

In the event of a serious accident, external cooling can be applied to the lower head of the reactor pressure vessel (RPV) in order to reduce the possibility of damage to the lower head. However, there will be great heat flow surrounding the lower head of the RPV, so external cooling may cause subcooled boiling, which gathers bubbles and deteriorates heat exchange, even burns out. This research uses ANSYS Fluent to calculate the critical heat flux (CHF) for external cooling of the RPV, and it is found that the nucleation density model studied by Basu Warrier and Dhir can be well applied to the calculation of CHF on the spherical surface. By comparing the CHF of the spherical and ellipsoidal lower head, it is believed that the CHF characteristics of the ellipsoidal lower head are completely different from the spherical structure. The experimental and calculation results of the spherical structure cannot be used to infer the numerical value and variation of the ellipsoidal structure.